1. Field of the Invention
This invention is directed to wellbore milling systems and methods; and, in one particular aspect, to such systems and methods for milling through a liner that projects into a lateral wellbore from a main wellbore to re-establish a pathway to the main wellbore.
2. Description of Related Art
The prior art discloses a wide variety of wellbore milling systems and methods and a wide variety of systems and methods for re-establishing a pathway through a main wellbore after lining a lateral wellbore with a liner. Many such prior art systems and methods require a guide for a milling system so that the milling system mills back through the liner rather than entering the liner itself and milling in the wrong location. Without such a guide a lateral liner can be damaged by the wrongly located milling system, and the pathway through the main wellbore will not be re-established.
Various prior art systems which do not employ a mill guide use a milling system on a rotatable tubular string. If such a string is not sufficiently stiff and is not sufficiently stable, a mill at the end of the string may preferentially attempt to enter a lateral liner rather than mill through the liner to reestablish communication through another (e.g. primary) wellbore.